Mark Robinson last night praised a five-wicket haul for opening bowler Lewis Hatchett.
But the Sussex coach admitted his side might have bowled out hosts Durham more cheaply.
Durham made 337 on the opening day of the LV County Championship tussle at Riverside yesterday in conditions which assisted swing bowling.
Sussex survived six overs before stumps to close on 20-0.
Hatchett took 5-113, including two of the early strikes which had Durham struggling at 30-3 having won the toss.
Robinson said: “It’s fantastic for Lewis to get his five wickets.
“He would probably have liked to have gone for a few less runs but it will be a good confidence boost for him.
“The ball swung and we had them in trouble.
“They counter-attacked then and again when we had them seven down (for 202).
“There was a bit of playing and missing as well. We would have liked to have got them out for 250 and, on another day, we might have done.
“But it is very hard to say what kind of a score that is until we bat.”